The invention generally relates to blood collection and processing systems and methods. In a more particular sense, the invention relates to systems and methods for removing white blood cells from red blood cells prior to transfusion or long term storage.
Systems composed of multiple, interconnected plastic bags have met widespread use and acceptance in the collection, processing and storage of blood components.
Before storing red blood cells for later transfusion, it is believed to be desirable to minimize the presence of impurities or other materials that may cause undesired side effects in the recipient. For example, because of possible febrile reactions, it is generally considered desirable to store red blood cells with a reduced number of xe2x80x94leukocytes. Filtration is conventionally used to accomplish leuko-reduction.
Systems and methods for reducing the number of leukocytes by filtration in multiple blood bag configurations are described. e.g., in Stewart U.S. Pat. No. 4,997,577, Stewart et al. U.S. Pat. No. 5,128,048, Johnson et al U.S. Pat. No. 5,180,504, and Bellotti et. al. U.S. Pat. No. 5,527,472. In these filtration systems and methods, a transfer assembly dedicated solely to the filtration of leukocytes from red blood cells is used. The transfer assembly also has a second fluid path that bypasses the filtration for the purpose of transferring liquid or venting air around the separation device.
In addition, before transfusing stored cellular blood components like red blood cells, it is important to assure that the blood type of the recipient matches the blood type of the donor. For this reason, conventional blood collection procedures collect several small aliquots or samples of the donated blood component for use in crossmatching and typing the donor""s blood prior to transfusion.
FIG. 1A shows a representative conventional system that filters leukocytes from red blood cells, vents air from the filtered cells, and creates segmented aliquots of the filtered cells for crossmatching and typing purposes. In use, red blood cells are conveyed from a transfer bag 1 through a leukocyte reduction filter 2 into a storage bag 3. An in-line clamp C controls this flow. Once filtration is completed, the storage bag 3 is squeezed to expel air through a bypass line 4 around the filter 2 into the transfer bag 1. An in-line check valve CV permits one-way fluid flow toward the transfer bag 1, but blocks fluid flow in the opposite direction toward the storage bag 3. A conventional heat sealing device (for example, the Hematron(copyright) dielectric sealer sold by Baxter Healthcare Corporation, not shown) forms a hermetic, snap-apart seal X1 in the tubing just downstream of the filter 2. The system components upstream of the seal X1 are disconnected and discarded. As FIG. 1B shows, the remaining tubing 5 (still attached to the storage bag 3) carries alpha or numeric identification markings 6 (which may also be machine-readable), which are printed in a spaced-apart pattern along its length. As FIG. 1A shows, a label 7 on the storage bag 3 carries the same identification markings 6. Using a conventional blood tube stripper (also not shown), the technician displaces residual air from the remaining tubing 5 into the storage bag 3. Upon removal of the tube stripper, the air displaced into the storage bag 3 expels filtered cells into the remaining tubing 5 to occupy the numbered segments 6. As FIG. 1D shows, the sealer is then used to form sealed, snap-apart seals X2 between the identification markings 6, creating segmented pockets 8 where the samples of the filtered cells are retained. The donor-specific label 7 is removed from the transfer bag 1 and attached to the storage bag 3, to thereby preserve a link between the transfer bag 1, the storage bag 3, the numbered blood segments 8, and the donor.
Alternatively, as shown in FIGS. 1A and 1C, the conventional storage bag 3 can also include an a attached tubing segment, or xe2x80x9cpigtailxe2x80x9d P, which carries the same identification markings 6 printed in a spaced-apart pattern along its length. Once filtration and air venting is completed, the technician uses the blood tube stripper to displace residual air from the pigtail P into the storage bag 3, which in turn displaces filtered cells into the pigtail P. The sealer can then be used to form sealed, snap-apart pockets, as before described, one for each numbered segment, where the samples of the filtered cells are retained.
Prior techniques require the technician to perform multiple, separate functional steps. First, the technician must vent air from the storage bag. Then, the technician must pick up and operate a tube stripper, to expel blood from the storage bag into tubing to create segmented samples for crossmatching and blood typing.
The invention provides more straightforward and convenient systems and methods to remove undesired matter from blood cells, which permit air venting and sample expulsion to take place in one functional step. The invention obviates the need for tube strippers, thereby simplifying the overall blood manipulation process. Still, the invention assures that accurate crossmatching and typing of the blood occurs.
One aspect of the invention provides a blood processing assembly comprising a blood receiving container having first and second ports. A first flow path is included, which has an inlet region for coupling the first flow path in fluid communication with a blood source container and an outlet region coupled to the first port. The first flow path includes a separation device positioned between the inlet and outlet regions that separates undesired matter from blood en route the blood receiving container. A second flow path is also included, which has an entry region coupled to the second port, and not the first port, and an exit region coupled to the inlet region of the first flow path at a junction. The second flow path includes a one-way valve between the entry region and the exit region. The one-way valve permits fluid flow through the second flow path, bypassing the separation device, only from the blood receiving container toward the blood source container and not vice versa.
Another aspect of the invention provides a method of using the assembly. The method directs blood through the first flow path and separation device to remove undesired matter. The blood is collected in the blood receiving container after passage through the separation device. The method squeezes the blood receiving container to expel residual air from the blood receiving container through the second flow path. The one-way valve permits air flow only in a direction away from the blood receiving container, and not vice versa. The method squeezes the blood receiving container to convey a sample of blood from the collection container into the second flow path. Again, the one-way valve permits blood flow only in the direction away from the blood receiving container, and not vice versa. The method seals the second flow path to retain the sample of blood in the second flow path.
By virtue of the above described structure and method of use, a sample of blood from the blood receiving container can be transferred into the second flow path simply by squeezing the blood receiving container, and coincident with air venting. There is no need for separate air venting and blood sample collecting steps, and there is no need for a tube stripper.
In a preferred embodiment, the separation device removes leukocytes from blood.
Other features and advantages of the invention will become apparent upon review of the following description, drawings, and appended claims.